Bright yellow sunflowers add cheerful color to the garden, with many seed-producing varieties reaching 5 feet or more in height. In fall, they release their seeds, which are quickly eaten by birds and wildlife if you aren't quick to harvest them. Knowing when the seeds are about to ripen and harvesting them immediately allows you to save and roast them for your own use. A few simple measures will keep the birds and animals at bay.
Check the back of the sunflower's disk (head) once the petals begin wilting. Place a mesh sack or nylon stocking over the flower disk once it begins to turn from green to yellow. Tie a string around the stem and bag opening to hold it closed. This prevents birds and squirrels from accessing the ripening seeds.
Cut off the flower disk with a knife when the back turns brown. Leave 1 foot of stem attached and leave the bag on the disk when cutting. Sunflower seeds are fully ripe when the back of the disk is brown and the seeds begin loosening and falling off on their own.
Hang the flower disk upside down by the stem in a warm, dry room. Let the disk finish drying for another week.
Remove the bag and shake out any seeds from it that have already fallen off the flower disk. Brush your hand over the front of the disk to dislodge any remaining seeds.
Store the seeds in an air-tight container until you are ready to use them. Alternately, roast the sunflower seeds first in a 300-degree F oven for 25 minutes, then store.